Triangle Classificaition with Geometer's Sketchpad.

Given a pair of parallel lines and a triangle in between, geometers prove that the sum of the interior angles is 180 degrees. This quick quest can be used as a pop quiz or exit ticket for your geometry class.

After reviewing characteristics of seven types of triangles, young geometers discover how to find the missing angle of a triangle. Then, they practice identifying triangles, find missing angles, and find missing side lengths of similar...

Why are there so many different types of triangles? Be that as it may, beginning geometers need to understand the differences between equilateral, isosceles, scalene, and right triangles, and they get a visual approach with this...

Stuck with triangle proofs? Take a 180° and provide learners with a guided worksheet that tests their knowledge with triangle inequalities. The questions require different types of proofs that range in levels of difficulty. 

How are angles and sides related? Given several regular convex polygons, the video shows how to calculate the sum of their interior angles. The segment in a playlist on geometry shows how to find the measure of one angle if the polygon...

Base your calculations of the areas of triangles on their bases. An illuminating video in the Socratica Geometry playlist explains how to determine the areas of a triangle. The video uses an animation to illustrate how triangles with the...

Learn how to identify an equilateral triangle by evaluating its congruent sides. Once you've determined that that sides are congruent you'll be able to use the triangle sum theorem to determine the angles in an equilateral triangle. This...

Determine whether it is right or not. Using the Pythagorean Theorem, the video shows how to determine whether a triangle is a right triangle. Pupils practice the skill in a few of the problems in the associated worksheets on the...

Squares, pentagons, triangles, polygons. How is it possible to figure out the sum of the interior angles of any of these multi-faceted shapes? There's got to be a formula. Of course there's a formula. That's what algebra is all about,...

Finding the missing values of two angles in an isosceles triangle is not as difficult as it sounds. But how can two out of three angle's measurements be found? Well, there are special properties about an isosceles triangle which make...